In a different time, Sharon Van Etten could have been a folk-based singer-songwriter in the mold of Kath Bloom, with an overflowing heart communicated through a throaty tremolo; or possibly a gauzy romantic along the lines of Mazzy Star’s Hope Sandoval and David Roback, all languid vocals and spacious acoustic strums. On “Tramp,’’ her third album, she embraces both approaches. Thus, the opening one-two punch of “Warsaw’’ and “Give Out’’ initially seem to have all the hallmarks of the latter group, but the guitars are too hard-hit, her voice isn’t quite as detached, and there’s fire burning determinedly at all turns. “Serpents’’ ups the ante, with two Van Ettens restlessly searching over an agitated snare drum for someplace to land and never finding it, leaving the song no worse for wear. For a few tracks, like “Magic Chords,’’ her sound starts becoming a trap for a song that never quite coalesces. But the flip side is “All I Can,’’ which reveals a streak of slow-build adult pop craft that’s kept under wraps for much of the album. (Out now)